1997 Ls 400 Won't Rev Beyond 4000

[jac430]

My LS430 has a Toyota Denso air flow meter.

The brand is clearly visible:

I suppose the LS400 is similar.

Jac

[MUDGUTS]

My LS430 has a Toyota Denso air flow meter.

The brand is clearly visible:

I suppose the LS400 is similar.

Jac

Thanks Jac, I'll have a look on the web. I had a reply from Toyota and Lexus parts last night with a picture in it which I have saved. I'll try to post this.

The part No. on that is: 22250

[MUDGUTS]

My LS430 has a Toyota Denso air flow meter.

The brand is clearly visible:

I suppose the LS400 is similar.

Jac

Thanks Jac, I'll have a look on the web. I had a reply from Toyota and Lexus parts last night with a picture in it which I have saved. I'll try to post this.

The part No. on that is: 22250

Here is the Pic with the part No. on it:

It looks like the part No. on yours cointains '22204 - 22210' My guess is that I need one that has a range that includes '22250' this must be some kind of operating range...

[jac430]

Yes, it seems a bit different from the LS430.

I looked it up in the Toyota/Lexus catalogue and indeed it seems that you would have to replace the whole assy.

The actual air flow meter sensor is quite small.

I made a photo of the interior of the sensor in my LS430 (which is in the air stream):

You could try cleaning it with a spray can of MAF cleaner, if you have not done that already.

Sorry I can't be of more help to you.

Jac

[MUDGUTS]

Thanks Jac.

I'll get the car home and give this a try once I know this is the culprit, If it is faulty there is nothing to lose by trying a spot of MAF cleaner.

[MUDGUTS]

I have changed the MAF sensor for a used unit today and the fault is EXACTLY the same. Looks like it will have to go to Lexus today.

[Parrot of Doom]

Disconnect the Battery for half an hour.

[MUDGUTS]

Disconnect the battery for half an hour.

I though about doing this or trying to reset the ECU. I remember something about ECUs needing to be reset after a new component has been fitted...Have taken it to Lexus MK to see if they can diagnose the problem. The technician sat in it with me and thinks it has a misfire (crap plugs / leads / coil pack). These guys should be able to get to the problem even if I have to replace stuff myself later.

This is the problem with cars, you need lots of time to tinker with them, if I had serious time I could have probably tried plugs and tried other stuff. I'm either away with work or on call so dealing with this takes a long time and has to be fitted in. Now I look back I maybe should have taken in straight to the Lexus guys, but then you could be spending lots of money sorting a simple problem.

Otherwise it seems to be good...A couple of minor things I can live with or tinker with when I am free.

[ambermarine]

Disconnect the battery for half an hour.

I though about doing this or trying to reset the ECU. I remember something about ECUs needing to be reset after a new component has been fitted...Have taken it to Lexus MK to see if they can diagnose the problem. The technician sat in it with me and thinks it has a misfire (crap plugs / leads / coil pack). These guys should be able to get to the problem even if I have to replace stuff myself later.

This is the problem with cars, you need lots of time to tinker with them, if I had serious time I could have probably tried plugs and tried other stuff. I'm either away with work or on call so dealing with this takes a long time and has to be fitted in. Now I look back I maybe should have taken in straight to the Lexus guys, but then you could be spending lots of money sorting a simple problem.

Otherwise it seems to be good...A couple of minor things I can live with or tinker with when I am free.

Hi

In defence of the Lexus service I can't say that I feel I have paid over the odds for anything they have done on my car in 16 years they will diagnose the problem a lot quicker than anyone else and they will tell you truthfully and precisely what needs doing before they will start any work or replacement of parts.

Now if you then resolve to fix the problem somewhere else you have the option,and they don't fall out with you, in fact when I had replacement parts fitted to my LS400 back in 2000 The lexus dealership fitted the parts I had sourced in the USA charging only for the labour but with the proviso there was no guarantee on the parts or subsequent knock on effects to other components.

I try to fix the fixable things on my car but inevitably there will come a time that this can only be done in a Lexus workshop and I think in my particular situation that will mean a new Lexus as the values of a 1990 or pennies and any serious engine or transmission fault would spell curtains for this old girl.

[Malc]

As one never hears of a engine or transmission fault in these dear old ladies does that mean you will be keeping it for ever ?

Malc

[MUDGUTS]

Disconnect the battery for half an hour.

I though about doing this or trying to reset the ECU. I remember something about ECUs needing to be reset after a new component has been fitted...Have taken it to Lexus MK to see if they can diagnose the problem. The technician sat in it with me and thinks it has a misfire (crap plugs / leads / coil pack). These guys should be able to get to the problem even if I have to replace stuff myself later.

This is the problem with cars, you need lots of time to tinker with them, if I had serious time I could have probably tried plugs and tried other stuff. I'm either away with work or on call so dealing with this takes a long time and has to be fitted in. Now I look back I maybe should have taken in straight to the Lexus guys, but then you could be spending lots of money sorting a simple problem.

Otherwise it seems to be good...A couple of minor things I can live with or tinker with when I am free.

Hi

In defence of the Lexus service I can't say that I feel I have paid over the odds for anything they have done on my car in 16 years they will diagnose the problem a lot quicker than anyone else and they will tell you truthfully and precisely what needs doing before they will start any work or replacement of parts.

Now if you then resolve to fix the problem somewhere else you have the option,and they don't fall out with you, in fact when I had replacement parts fitted to my LS400 back in 2000 The lexus dealership fitted the parts I had sourced in the USA charging only for the labour but with the proviso there was no guarantee on the parts or subsequent knock on effects to other components.

I try to fix the fixable things on my car but inevitably there will come a time that this can only be done in a Lexus workshop and I think in my particular situation that will mean a new Lexus as the values of a 1990 or pennies and any serious engine or transmission fault would spell curtains for this old girl.

I think you could have a point there ambermarine. The money I have spent with a local (although reasonable) garage chasing this may have been better spent having Lexus diagnose the fault in the first place. Having said that, they would have also found the duff oxy sensor and I would have had them change this. That would have been more expensive than having an independent do it.

[MUDGUTS]

Disconnect the battery for half an hour.

I though about doing this or trying to reset the ECU. I remember something about ECUs needing to be reset after a new component has been fitted...Have taken it to Lexus MK to see if they can diagnose the problem. The technician sat in it with me and thinks it has a misfire (crap plugs / leads / coil pack). These guys should be able to get to the problem even if I have to replace stuff myself later.

This is the problem with cars, you need lots of time to tinker with them, if I had serious time I could have probably tried plugs and tried other stuff. I'm either away with work or on call so dealing with this takes a long time and has to be fitted in. Now I look back I maybe should have taken in straight to the Lexus guys, but then you could be spending lots of money sorting a simple problem.

Otherwise it seems to be good...A couple of minor things I can live with or tinker with when I am free.

Hi

In defence of the Lexus service I can't say that I feel I have paid over the odds for anything they have done on my car in 16 years they will diagnose the problem a lot quicker than anyone else and they will tell you truthfully and precisely what needs doing before they will start any work or replacement of parts.

Now if you then resolve to fix the problem somewhere else you have the option,and they don't fall out with you, in fact when I had replacement parts fitted to my LS400 back in 2000 The lexus dealership fitted the parts I had sourced in the USA charging only for the labour but with the proviso there was no guarantee on the parts or subsequent knock on effects to other components.

I try to fix the fixable things on my car but inevitably there will come a time that this can only be done in a Lexus workshop and I think in my particular situation that will mean a new Lexus as the values of a 1990 or pennies and any serious engine or transmission fault would spell curtains for this old girl.

I think you could have a point there ambermarine. The money I have spent with a local (although reasonable) garage chasing this may have been better spent having Lexus diagnose the fault in the first place. Having said that, they would have also found the duff oxy sensor and I would have had them change this. That would have been more expensive than having an independent do it.

...The latest is that the Lexus dealer can't find the fault and 'suspect' the distributor. To replace this would involve some serious labour.

I would be very grateful for any input.

[beavisrules]

Distributors do wear out , and are usually obvious from burnt/eroded contacts (sparks vaporizing the metal).

If it is an ignition problem , might be worth buying a colour tune plug or similar.

basically a light that goes between the spark plug and lead.

some actually replace the plug with a sort of glass see through plug so you can see it firing.

change from a tenner for a cheap one off of fleabay .Or the better gunson ones are there too for £20-30.

just search for spark test in the vehicle section

but then again , its not that hard of a job to change the lot , and I'm sure one of the spares people on here could sell you a tested/used complete dizzy/leads/rotor setup for not too much.

[MUDGUTS]

Distributors do wear out , and are usually obvious from burnt/eroded contacts (sparks vaporizing the metal).

If it is an ignition problem , might be worth buying a colour tune plug or similar.

basically a light that goes between the spark plug and lead.

some actually replace the plug with a sort of glass see through plug so you can see it firing.

change from a tenner for a cheap one off of fleabay .Or the better gunson ones are there too for £20-30.

just search for spark test in the vehicle section

but then again , its not that hard of a job to change the lot , and I'm sure one of the spares people on here could sell you a tested/used complete dizzy/leads/rotor setup for not too much.

Thanks beavisrules, I just don't have the time to get into this myself, so have left it with the Lexus dealer to do. I have asked that they replace the HT leads and plugs first then if that fixes it, I'll make the decision as to whether or not to let them push on and change the Distributor caps. If it does I'm tempted to have them done whilst they are in there and if not, I'll have to let them anyway...

Failing this, it looks more expensive. I hope not.

I was tempted to get the independant do this but, although the labour rate may be less, they could easily take longer as they won't have the experience. It's a tough call with this as the dealer won't guarantee this will fix the problem... I know its a sound car, it pretty much went straight through the MOT and drives straight, with no suspension issues, no clonking, not issues with the transmission, etc. it's just frustrating to get a car like this and have problems from the beginning.

[ambermarine]

As one never hears of a engine or transmission fault in these dear old ladies does that mean you will be keeping it for ever ?

Malc

Hi Malc

In answer to that very question, hopefully ,I remember that when I first got the car and had it regularly serviced at the Lexus dealership a Salesman tried to interest me in the Mark 3 which had just arrived .I informed him as far as Lexus were concerned they could quote for the job of painting the red car I have, black for my funeral,needless to say his sales pitch stalled, never to start again.

The only thing that will destroy the car is rust ,I have had to have some cill repairs forward of the rear wheel arch both sides they rust from the inside and on the early cars the rear wheel arches rusted above the wheel but I got onto that early and have contained it, need to go back every couple of years when the paintwork bubbles and base it but I have succeeded so far in keeping it at bay.I have fixed and repaired most everything mechanically that needed renewing through wear and tear.

Replaced the climate control lcd myself which involved several dozen emails back and forth with the supplier in California because he supplied a faulty one, I had a very swift sixteen hour electronics lesson in soldering bridges and auxillary pcbs after that experience I feel part of me is in the car now.

The recent bushing replacement as given her a new lease of life and I take great pleasure in the fact that after 21 years she is still around.

[abs66]

Hi Mudguts, I'm curious as Beavis asked, does it stop dead at 4000 rpm remaining smooth or does it hunt up and down just around 4000 rpm?

Did you say you had tried removing the Battery for 30 mins yet? Sorry if you have answered this already somewhere I just havent seen it! Need my eyes testing methinks!

[MUDGUTS]

Hi Mudguts, I'm curious as Beavis asked, does it stop dead at 4000 rpm remaining smooth or does it hunt up and down just around 4000 rpm?

Did you say you had tried removing the battery for 30 mins yet? Sorry if you have answered this already somewhere I just havent seen it! Need my eyes testing methinks!

Hi abs66, no it is around 4000 RPM, 'blipping' the throttle gets a slightly higher RPM like maybe 5000. There is no fixed point that would lead me to believe its an imposed limit, it just won't rev right up. Never tried disconnecting the batt, I should have...

Should know more on Monday

[abs66]

I was just wondering as I got the feeling it may be ECU related and a Battery removal reset wouldn't do any harm.

I don't know whether the guys that do superchip replacements or remapping might be able to check the ecu for you, chances are they have come across working ones and therefore might be able to tell you if yours is duff.

It almost seems like fuel starvation too I wonder can you smell petrol at all?

I'm probably wrong but I've never come across faulty leads/plugs/coils/dizzy caps that only seemed to be faulty at one particular rev range, but I may have just been lucky over the years

[beavisrules]

I've had coils that cant produce enough energy at higher revs before but that was in the days of old oil filled coils.

If it is OBD2 compatible , I cant see why Lexus dealer cant take live readings from all the sensors.

If its misfiring the o2 sensors will sense unburnt fuel

Recently used one with the OPcom software on my old mans vectra - was quite in depth , can see the Throttle position , fuel pressure , voltage return states from coils/injectors and a load of other things i knew nothing about.

If anyone has ideas on what software to use with an LS , I am game to have a try with my assortment of cables.

[MUDGUTS]

Thanks Guys, at this stage the Lexus dealer has assured me that to replace Plugs, HT Leads, Dis. caps and Rotors is the best course of action. As I said before the lack of a definitive cause is frustrating. The Tech that sat in the car with me thought it was a misfire under load, this may be why it blips to over 5000 but won't hold more than about 4000 whilst on the move.

[bazgtr]

A failing fuel pump or blocked pickup filter in the tank would also cause similar problems.

I once had a car with a failing fuel pump, each week the rev limit got lower and lower until I had to change it!

I've jusy answer this in the other thread as didn't see this thread aswell.

Firstly it's NOT A MISS. Reason it's a V8 and unless you have four misses then power won't change that much or the rev limit. If it was a miss you would be ticking over with a miss or have it on first start up when the leads are damp before they warm up and clear the damp and the miss(Two miles into a journey).

As you hit the throttle it becomes an under load problem. Air/ Fuel mixture or if it was a turbo car then it would be an air leak somewhere.

Try Mass Air Flow meter.

Baz.

[MUDGUTS]

Plugs, HT Leads, Dis. caps and Rotors all changed and the problem is still there. If I can't get this fixed in the next week, it's going to the scrapyard.

[cleverdick]

Hi,

Just looking at the matrix chart for the '91, most of which should still apply (although you've eliminated most of it)...

For "Hesitation/Poor acceleration" it lists:

Ignition Signal Circuit, Main Oxygen Sensor Circuit, Water Temp Sensor Circuit, Intake Air Temp Sensor Circuit, Air Flow Meter Circuit, Throttle Position Sensor Circuit, EGR System, Injector Circuit, Cold Start Injector Circuit, Fuel System Circuit, Fuel Quality, Vacuum Leakage, Spark Plug, Ignition Coil, Distributor, Accelerator Pedal Link, Brakes drag when released, Sub Throttle Valve faulty, ECT faulty, Engine Mechanical & Others, Engine & ECT ECU.

It then suggests:

Valve Timing, Timing Belt, Piston Ring.

Well, you can cross off 80% of that lot, and just a thought - has there been any work done on the transmission? If somebody forgot to reconnect a plug somewhere, it might think it's in a low gear which will also limit the RPM.

[abs66]

Er....do we know if the Battery has been disconnected for 30 mins yet?

Does anyone know if the boot loom prob has had this effect before? I heard it can produce some odd effects!

It does feel like its not getting fuel or thinks it isn't at more than 4000 revs.

Was the other MAF you tried deffo OK on another car or was it a straight 2nd hand swap with no proof that it was OK?

If someone had a couple of coils you could try that would help eliminate that possibility.

Also I know I might be well off the mark but I would try removing the air filter for a quick test but obviously don't leave it out. (Unless you have just bought a new one)

Wishing you luck so as she doesn't end up in the scrap yard. And if you do end the scrap yard route flog some of the new bits you have put on no doubt someone on here will be happy to take em of your hands for a price, I know I'm always on the look out for a radio with working display (not holding breath!)

Don't give up hope yet though I'm sure someone will have a brainwave, these guys on here are brilliant at hunting down a problem, fantastic club.

Fingers crossed

[ambermarine]

Plugs, HT Leads, Dis. caps and Rotors all changed and the problem is still there. If I can't get this fixed in the next week, it's going to the scrapyard.

Hi Mudguts

I have only come up with one possible fault which proved to be correct in the oxygen sensor but as you have discovered it is not the fault that is causing the problem.

And having eliminated several other contenders and baffled the Lexus techs I think you should try this suggestion as a last shot before you give the car a recycling ticket.

If we assume that all is well in the electronic information department from fuel and electrics and this information is reaching the engine and gearbox ecu, there could be the problem.The main engine management ecu could be either mis-interpreting the information or sending out the wrong information ,bearing in mind that the ECU receives information from the gearbox and the engine then processes that information to issue commands to both units . There are a couple of ebayers who regularly sell ls400 parts ,try a different ecu they can be had for £50 .

Its worth a shot you can always sell it again if it is not the answer